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Biomedical subjects

W Huang

Publications and source records attributed to W Huang.

At least 505 records · Page 28Linked to original sources
PubMed1996

[Immunoglobulin super-gene family and its related genes in detecting MRD in ALL].

OBJECTIVE: To study the rearrangements of the immunoglobulin super-gene family and its related genes, as well as their application in the detection of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL). METHODS: 15 ALL cases including 11 B-ALLs and 3 T-ALLs were studied separately by using immunophenotype detection and molecular clonging methods. RESULTS: Using DNA Southern blot analysis, we found that the rearrangement of IgH gene existed in 11 B-lineage ALL cases. The specific PCR band was visualized through amplification of the CDR3 region and J region of IgH gene. Furthermore, we sequenced the V-D-J junctional region of IgH gene in 3 B-lineage patients and synthesized two probes against the V-D-J junctional region in order to detect MRD. The hybridization results showing the sensitive of the two probes were 10(-4). In addition, we performed comparative study of MRD detection by using both T cell receptor (TCR) gamma gene as gene specific marker and SIL-TAL-1 fusion gene as tumor-specific marker in one T-ALL patient. CONCLUSION: The rearrangements of IgH gene, as well as TCR gene and tumor fusion gene can be used as specific markers in the detection of MRD in ALL.

Adolescent↗
PubMed1996

[Expression of tissue-type plasminogen activator (t-PA) in smooth muscle cells of injured iliac arteries in rabbits].

To investigate the mechanism of atherogenesis and development of restenosis following angioplasty, the expression of t-PA in SMC at different intervals after the arterial injury was measured by morphological analysis, plasmin generation assay and in situ hybridization. t-PA activity of the iliac arteries was noticed to be significantly increased on the 4th day after injury, signalling the commencement of SMC migration from the media to intima, t-PA activity then decreased to approximately the normal level on the 7th day. Results from in situ hybridization also showed that the expression of t-PA mRNA in the intima and media increased significantly on the 4th day after the arterial injury, by the 7th day, t-PA mRNA was detected only in SMC located adjacent to the internal elastic lamina. These results suggest that t-PA might play an important role in SMC proliferation and migration following arterial injury.

Angioplasty, Balloon, Coronary↗
PubMed1996

[The effect of electro-acupuncture on the adrenal gland of endotoxic shocked rats].

The quantitative histochemical changes of glycogen SDH in the adrenal gland of endotoxic-shocked rat induced by electro-acupuncture were observed in this paper. The result indicates that electro-acupuncture at "Ren Zhong" or "Zusali" of endotoxic shocked animal might improve the function of adrenal cortex and achieve recovery in certain extent.

Adrenal Glands↗
PubMed1996

Serum haptoglobin suppresses T-lymphocyte functions following burns.

It is well known that serum immunosuppressive factors play an important role in the mechanism of postburn immunosuppression. This study was intended to investigate the effect of haptoglobin, purified from the serum of burned patients by affinity chromatography, on the proliferation and interleukin-2 (IL-2) secretion of normal murine thymocytes induced by ConA and the proliferation of IL-2 dependent cell line (CTLL-2) stimulated by recombinant human IL-2, so as to elucidate the role of serum haptoglobin in postburn T-lymphocyte dysfunction. The results showed that purified haptoglobin, at the level equivalent to the concentration found in serum of burned patients, significantly inhibited the proliferation and IL-2 secretion of normal murine thymocytes as well as CTLL-2 proliferation; whereas it exhibited no immunosuppressive effects at the level equivalent to the concentration found in serum of normal volunteers. According to the results reported here, it is suggested that extraordinary increase in serum haptoglobin level may be an important factor of impaired T-lymphocyte responses following burns.

Animals↗
PubMed1996

Expression of tissue-type plasminogen activator in smooth muscle cells of injured iliac arteries in rabbits.

In this experiment, expression of tissue-type plasminogen activator (t-PA) in smooth muscle cells (SMCs) was measured at different intervals after the arterial injury. In the normal iliac arteries, only low levels of t-PA activity were estimated. t-PA activity in extracts of the iliac arteries increased significantly at the 4th day after the injury, equivalent to the process that SMCs migrated from the media to the intima, and the t-PA activity was then decreased approximately to the normal level at the 7th day. Coexistent to the above data, results from in situ hybridization showed that the expression of t-PA mRNA in the intima as well as media increased also significantly at the 4th day after the arterial injury, and at the 7th day, t-PA mRNA was detected only in those SMCs locating closely adjacent to the internal elastic lamina. These results suggest that t-PA might play an important role in SMC migration following endothelial injury, and antagonism of t-PA expression and/or activity within the vessel wall might be helpful in intervening the development of restenosis following angioplasty.

Angioplasty, Balloon↗
PubMed1996

[The role of thermal injury on nitric oxide (NO) production by mouse macrophages and its possible mechanism].

To study the production NO by macrophages (M phi) after burn injury and the possible mechanism, we determined the NO production and the iNOS (inducible NO synthase) activity of peritoneal M phi (PM phi) in scald mouse, and the effect of iNOS specific blocker NMMA. Actinomycin D (AD) and protein tyrosine kinase (PTK), special inhibitor Genisteinon them in vitro. It was found that PM phi produced excessive NO in the early postburn phase and the iNOS activity was increased significantly, and there was a positive correlation between them. NMMA, AD as well as Genistein could inhibit the NO production, the activity of iNOS was decreased by both AD and Genistein. The results suggested that M phi was activated after thermal injury and it could produce NO excessively through initiating iNOS synthesis. PTK signal system was involved in the NO production by M phi via affecting the iNOS synthesis after burn injury.

Animals↗
PubMed1996

[Clinical correlations of multidrug resistance gene expression in ovarian carcinoma].

OBJECTIVES: To measure the multidrug resistance gene (MDR1) messenger RNA (mRNA) content of ovarian carcinoma and to investigate the clinical significance of MDR1 expression in ovarian carcinoma. METHODS: A sensitive assay based on the polymerase chain reaction (PCR) was used to measure MDR1 mRNA in biopsy samples of 35 ovarian carcinoma, 20 ovarian benign tumors and 17 normal controls. Pathological diagnosis was made from these samples. RESULTS: (1) The expression rate of MDR1 in ovarian carcinomas was 57.1%, but there was no expression in benign ovarian tumors and in the normal controls. (2) 40.9% of patients given primary treatments and 84.6% of patients previously treated but with relapses had over expression of MDR1 gene. (3) The positive expression rate of MDR1 in cancer lesion, its adjacent sites and metastasis was 52.9%, 11.8% and 70.6% respectively. (4) The response rate to chemotherapy was lower in patients with overexpression of MDR1 gene than in patients without such expression. (5) No significant correlation was observed when the positive rate of expression of MDR1 in cancer tissues was analyzed against clinical stages and pathological types. CONCLUSIONS: The overexpression of MDR1 was correlated with acquired drug-resistance in patients with ovarian caracinoma. Measurement of the expression of MDR1 in a patient's tumor may be of value clinically in detecting drug-sensitivity and in predicting prognosis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

[Dynamic effects of sulphuric gentamicin on vestibular function in guinea pigs].

Sinusoidal rotation and rotational stimulation tests were used to examine vestibular function in guinea pigs. The results showed that there was no statistically significant difference in the mean number of nystagmus of semi-cycle sinusoidal rotation test and the duration of nystagmus of rotational stimulation test for both the control and test groups before treatment in albinos and pigmented guinea pigs. Meantime, daily subcutaneous injection of gentamicin 125 mg/kg body weight for 12 days in albinos and pigmented guinea pigs showed no significant change in vestibular function until the 7th day of treatment. Significant impairment of vestibular function was noticed on the 10th treatment day. At 5 days after treatment vestibular impairment reached its maximum and minimal recovery was seen at 14 days after treatment. No Further improvement of vestibular function was noticed three months after treatment. The methods are feasible and reliable.

Animals↗
PubMed1995

Cloning, expression, and characterization of the TATA-binding protein (TBP) promoter binding factor, a transcription activator of the Acanthamoeba TBP gene.

TATA-binding protein (TBP) gene promoter binding factor (TPBF) is a transactivator which binds to the TBP promoter element (TPE) sequence of the Acanthamoeba TBP gene promoter and stimulates transcription in vitro. We have isolated a cDNA clone encoding TPBF. TPBF is a polypeptide of 327 amino acids with a calculated molecular mass of 37 kDa. The predicted amino acid sequence of TPBF shows no significant homology to other proteins. TPBF has two potential coiled-coil regions, a basic region, a proline-rich region, a histidine-rich N terminus, and a nuclear targeting sequence. The recombinant protein has an apparent molecular mass of 50 kDa, identical with that of TPBF purified from Acanthamoeba. Recombinant TPBF is able to bind DNA and activate transcription with the same specificity as natural Acanthamoeba TPBF, demonstrating the authenticity of the clone. Mobility shift assays of co-translated TPBF polypeptides and chemical cross-linking demonstrate that TPBF is tetrameric in solution and when bound to DNA. Analyses of TPBF mutants show that Coiled-coil II is essential for DNA binding, but Coiled-coil I and the basic region are also involved. TPBF is thus a novel DNA-binding protein with functional similarity to the tumor suppressor protein p53.

Acanthamoeba↗
PubMed1995

Early Homo and associated artefacts from Asia.

The site of Longgupo Cave was discovered in 1984 and excavated in 1985-1988 by the Institute of Vertebrate Paleontology and Paleoanthropology (Beijing) and the Chongqing National Museum (Sichuan Province). Important finds include very archaic hominid dental fragments, Gigantopithecus teeth and primitive stone tools. Palaeomagnetic analysis and the presence of Ailuropoda microta (pygmy giant panda) suggested that the hominid-bearing levels dated to the earliest Pleistocene. In 1992, joint Chinese-American-Canadian geochronological research corroborated the age using electron spin resonance (ESR) analysis. We report here that the hominid dentition and stone tools from Longgupo Cave are comparable in age and morphology with early representives of the genus Homo (H. habilis and H. ergaster) and the Oldowan technology in East Africa. The Longgupo dentition is demonstrably more primitive than that seen in Asian Homo erectus. Longgupo's diverse and well preserved Plio-Pleistocene fauna of 116 species provide a sensitive contextual base for interpreting the early arrival of the genus Homo in Asia.

Africa, Eastern↗
PubMed1995

Mechanism of an ATP-dependent carboxylase, dethiobiotin synthetase, based on crystallographic studies of complexes with substrates and a reaction intermediate.

The crystal structures of six complexes of homodimeric Escherichia coli dethiobiotin synthetase with a variety of substrates, substrate analogs, and products have been determined to high resolution. These include (1) the binary complex of dethiobiotin synthetase and the N7-carbamate of 7,8-diaminononanoic acid, (2) the binary complex of enzyme and the alternate substrate, 3-(1-aminoethyl)-nonanedioic acid, (3) the binary complex of enzyme with the product ADP, (4) the quaternary complex of enzyme, ADP, the N7-carbamate of 7,8-diaminononanoic acid, and Ca2+, (5) the ternary complex of enzyme, the ATP analog adenylyl (beta, gamma-methylene)diphosphonate, and the N7-carbamate of 7,8-diaminononanoic acid, and (6) the quaternary complex of enzyme, the ATP analog adenylyl (beta, gamma-methylene)diphosphonate, 7,8-diaminononanoic acid, and Mn2+. One molecule of each substrate binds to one monomer of the enzyme. ADP and the ATP analogue bind to the classical mononucleotide binding fold with the phosphate groups close to the phosphate binding loop Gly8--Thr16 between beta-strand beta 1 and the N-terminus of alpha-helix alpha 1. The adenine ring is bound in a pocket between beta-strands beta 6 and beta 7. In the quaternary complex with Mn2+, the metal binding site is found in the vicinity of the beta- and gamma-phosphate groups. Two oxygen atoms from the phosphates and oxygen atoms from the side chains of Asp54, Thr16, and Glu115 are ligands to the Mn2+ ion in the quaternary complex. In the complex with ADP and the N7-carbamate of 7,8-diaminononanoic acid prepared in the presence of Ca2+ ions, a different metal binding site is found. The Ca2+ ion is coordinated to an oxygen atom of the alpha-phosphate group of the nucleotide, the side chain of Asp54, and solvent molecules. The 7,8-diaminononanoic acid substrate molecule interacts with residues from both subunits, making the dimer the minimal functional unit. The diamino group binds between the loops after beta 2 and beta 4, and the terminal carboxyl group at the hydrophobic tail of the substrate interacts with the amino terminus of helix alpha 5 and with the side chain of Tyr187 in helix alpha 6 of the second subunit at the monomer-monomer interface. Strong additional electron density close to the N7 nitrogen atom of the 7,8-diaminononanoic acid substrate in some complexes indicates that, even in the absence of added bicarbonate in the crystallization mixture, the carbamylated intermediate is formed in the crystal.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Diphosphate↗
PubMed1995

Crystallization and preliminary X-ray diffraction analysis of glutathione peroxidase from human plasma.

The extracellular form of glutathione peroxidase from human plasma has been crystallized by the sitting-drop vapour-diffusion method. The crystals belong to tetragonal space group I4(1) with cell dimensions of a = b = 83.1 and c = 131.0 A. They diffract beyond 2.9 A resolution and have one dimer in the asymmetric unit. A self-rotation function analysis shows the possible (222) symmetry for the tetramers of this enzyme.

Journal Article↗
PubMed1995

Intrathecal injection of an oxytocin-receptor antagonist attenuated postnephrectomy natriuresis in the male rat.

We have previously shown that oxytocin (OT) is a major humoral mediator in postnephrectomy natriuresis. As immunoassayable OT has been demonstrated in the spinal cord, the aim of this investigation was to determine whether OT receptors in the spinal cord are also involved in this natriuresis. The experiments were performed on anesthetized male rats. Before acute unilateral nephrectomy, an oxytocin-receptor antagonist was injected intrathecally in the thoracolumbar region in rats. Postnephrectomy natriuresis was attenuated by this injection but not by intrathecal injection of artificial cerebrospinal fluid. Our results suggest that OT receptors within the spinal cord may influence the autonomic nervous regulation of renal function. In an additional experiment, intravenously infused hexamethonium did not prevent the adaptive natriuresis in the remaining kidney. We conclude that OT receptors in the spinal cord are involved in the postnephrectomy natriuresis, possibly as a component in the afferent signal pathway.

Animals↗
PubMed1995

Mechanistically different catalytic antibodies obtained from immunization with a single transition-state analog.

The variable-region peptide sequence and steady-state kinetic behavior are compared for a family of catalytic antibodies that arose from the same immune response to a transition-state analog. The crystal structure of the most catalytically active member of the family (17E8) has been solved to 2.5 A resolution and shows that the antibody active site contains a SerH99-HisH35 (H = heavy chain) catalytic dyad analogous to the Ser-His-Asp catalytic triad of serine proteases. The variable-region peptide sequence of the next most active antibody (29G11) differs from that of 17E8 by nine heavy-chain point mutations, and results from computer modeling suggest that the three-dimensional structure of 29G11 is similar to that of 17E8. In addition, 29G11 is an efficient catalytic antibody; it possesses 26% of the hydrolytic activity of 17E8. There is one active-site mutation in 29G11 compared to 17E8; position 99 of the heavy chain of 29G11 contains a glycine residue in place of the nucleophilic serine at this position in 17E8. Consistent with this mutation, results from pH-rate studies and hydroxylamine partitioning experiments indicate that in contrast to the catalytic mechanism of 17E8, the mechanism of 29G11-catalyzed esterolysis does not feature nucleophilic catalysis.

Amino Acid Sequence↗
PubMed1995

Endogenous bacterial toxins are required for the injurious action of platelet-activating factor in rats.

BACKGROUND & AIMS: Platelet-activating factor (PAF), an endogenous mediator for experimental sepsis, has been shown to induce shock and intestinal necrosis in vivo. However, it is unclear whether PAF exerts its injurious effects on the intestinal tissue directly or via synergism with other endogenous products. The aim of this study was to examine the role of endogenous bacterial products, such as endotoxin, in PAF-induced intestinal injury. METHODS: PAF (3 micrograms/kg) was injected intravenously into normally colonized rats, germfree rats, and normal rats pretreated with a combination of antibiotics, and the systemic response and intestinal injury were assessed. RESULTS: PAF did not cause prolonged shock, leukopenia, hemoconcentration, and bowel necrosis in germfree rats. When germfree rats were primed with a low dose (0.5 mg/kg) of endotoxin, the protection was lost. Combined treatment of the normally colonized rats with neomycin, polymyxin B, and metronidazole for 7 days largely protected the animal from PAF-induced shock and intestinal necrosis. CONCLUSIONS: PAF does not directly induce prolonged hypotension, hemoconcentration, persistent leukopenia, and gross intestinal necrosis but causes these changes via a synergism with endogenous bacterial toxins, presumably from the gut flora.

Analysis of Variance↗
PubMed1995

Permeability of the blood-brain barrier to amylin.

Amylin is co-secreted with insulin from the pancreas of patients with non-insulin dependent diabetes mellitus, and its deposition may contribute to the central nervous system (CNS) manifestations of this disease. Amylin, but not its mRNA, is found in brain, suggesting that CNS amylin is derived from the circulation. This would require amylin to cross the blood-brain barrier (BBB). We used multiple-time regression analysis to determine the unidirectional influx constant (Ki) of blood-borne, radioactively labeled amylin (I-Amy) into the brain of mice. The Ki was 8.99(10(-4)) ml/g-min and was not inhibited with doses up to 100 micrograms/kg, but it was inhibited by aluminum (Al). About 0.11 to 0.13 percent of the injected dose of I-Amy entered each gram of brain. Radioactivity recovered from brain and analyzed by HPLC showed that the majority of radioactivity taken up by the brain represented intact I-Amy. Capillary depletion confirmed that blood-borne I-Amy completely crossed the BBB to enter the parenchymal/interstitial fluid space of the cerebral cortex. Taken together, these results show that blood-borne amylin has access to brain tissue and may be involved in some of the CNS manifestations of diabetes mellitus.

Aluminum↗
PubMed1995

Glucocorticoids upregulate high-affinity, high-density lipoprotein binding sites in rat hepatocytes.

Glucocorticoid hormones (GL) regulate high-density lipoprotein (HDL) plasma concentrations by increasing synthesis and secretion of HDL by the liver. However, little is known about the effect of GL on the uptake and processing of HDL by hepatocytes (HEP). To investigate this question, we studied the effects of dexamethasone (DEX) on the expression of high-affinity HDL-binding sites via the specific binding and internalization of iodine-labeled apolipoprotein E (apo E)-free HDL3 in a culture of rat HEP. Specific binding and internalization of HDL3 decreased by 60% in cells cultured in the absence of DEX for 48 hours. At concentrations of 10(-7) and 10(-5) mol/L, DEX prevented the decrease, maintaining specific binding and internalization versus the control level (at 24 hours). HDL-binding sites with a Kd of 20 micrograms/mL were revealed on the surface of cultured HEP. HEP demonstrated a greater binding capacity in the presence of DEX at concentrations of 10(-7) and 10(-5) mol/L (125 v 45 ng/mg cell protein). The effect of the hormone has demonstrated to be dose-dependent at concentrations between 10(-9) and 10(-7) mol/L, leveling off at 10(-7). Higher concentrations did not induce a further increase in specific binding and internalization. Withdrawal of the hormone from culture medium was associated with a decrease in specific binding of the ligand by 60% in the following 24 hours. To investigate the effect of glucocorticoid deficiency on liver uptake of HDL in vivo, specific binding and internalization were studied in a culture of HEP isolated from adrenalectomized rats (AER) at 2 hours after seeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗